ARM: dts: qcom-msm8960: add missing clocks to the timer node

ARM: dts: qcom-msm8960: add missing clocks to the timer node

In order to fix DT schema warning and describe hardware properly, add
missing sleep clock to the timer node.

Solved by Dmitry Baryshkov on the APQ8064 SoC
Link: https://lore.kernel.org/all/20250318-fix-nexus-4-v2-6-bcedd1406790@oss.qualcomm.com/
Signed-off-by: Rudraksha Gupta <guptarud@gmail.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Link: https://lore.kernel.org/r/20250318-expressatt-solve-dts-errors-v1-1-14012a4bc315@gmail.com
Signed-off-by: Bjorn Andersson <andersson@kernel.org>